1. Field of the Invention
This invention relates to suspension systems for automotive vehicles and machines which receive mechanical shock, and more particularly to an adjustable damping system.
2. Description of Related Art
Dampers are used in connection with automotive suspension systems to absorb unwanted vibrations which occur during driving. To dampen unwanted vibrations, dampers are generally connected between the body and the suspension of the automotive vehicle. A piston assembly is located within the damper and is connected to the body of the automotive vehicle through a piston rod. Because the piston assembly is able to limit the flow of damping fluid within the working chamber of the damper when the damper is compressed or extended, the damper is able to provide a damping force which "smooths" or "dampens" vibrations transmitted from the suspension to the body.
The greater the degree to which the flow damping fluid within the working chamber is restricted by the piston assembly, the greater the damping forces which are provided by the damper. Accordingly, a "soft" compression and rebound stroke is produced when the flow of damping fluid in the working chamber is relatively unrestricted. In contrast, a "firm" compression and rebound stroke is produced when there is an increased restriction in the flow of damping fluid in the working chamber.
Because different driving characteristics depend on the amount of damping forces the damper provides, it is often desirable to have a damper in which the amount of damping forces generated by the damper is adjustable. One method for selectively changing the damping characteristics of a damper is disclosed in U.S. Pat. No. 4,890,858. This reference discloses a damping system in which a switch is used to control the damping characteristics of a suspension system. In the regard, the switch is used to control the position of a rotary valve inside each of the dampers in the suspension system. The rotary valve is in turn used to control the flow of damping fluid between the upper and lower portions of the working chamber so as to change damping characteristics.